High resolution morphological surface analysis is an integral part of biological investigations under both physiological and pathological conditions. The fine structure modifications induced during cell motility or cellular secretion are captured in a real time manner by scanning electron microscopy (SEM) analysis of quick-frozen cell surfaces. Similarly, surface morphological changes observed in purified sub-cellular organelles (late endosomes and lysosomes) during various experimental conditions can be powerfully visualized by SEM analysis. Surface analysis of bacteria and fungi can provide very useful information on their morphological changes under differential experimental conditions. Distinct from imaging obtained by transmission electron microscopy (TEM), the SEM analysis is capable of producing high-resolution images that have great depth of field yielding a characteristic three-dimensional appearance useful for understanding the fine surface structure of a sample. For this major reason both TEM and SEM should often both be applied in the investigation of ultrastructural morphology of biological samples. This is a resubmission application for funding of a state of the art high resolution scanning electron microscope and an associated cryotransfer system. The requested SEM will be part of the Analytical Imaging Facility (AIF), a multi user imaging resource, and available to all trained investigators. Currently, a much out of date JEOL JSM6400 SEM installed 1989, is present in the facility which does not fulfill the needs of these investigators. A new SEM is required to image high magnification (>20,000x) at low accelerating voltage (1-2 kV) with a high brightness electron source for detecting 10 nm gold with backscatter electrons. A cryotransfer station will enable imaging of hydrated samples to avoid the artifacts of dehydration. The common scientific need of the major user in this application is the ability to obtain high resolution surface imaging from cells, organelles or pathogens under different experimental conditions. The cryo field emission scanning electron microscope described in this application will allow the assembled major users to analyze fine structural aspect of endosomal biogenesis and surface receptor distribution;pathogen surface morphology, receptor location and elemental distribution;nanofabricated devices;nematode morphology;and granule secretion which will be otherwise precluded.